1. Field of Invention
The present invention relates to sealing equipment, and more particularly to a portable vacuum device which has enhanced efficiency, is smaller in size, and is more convenient for utilization.
2. Description of Related Arts
Conventional sealing equipments, such as vacuum devices, have been extensively utilized for a wide variety of purposes, such as domestic vacuum sealing of storage bag which contains food. In the absence of air within the storage bag, the amount of micro-organisms would be kept minimum and therefore the extent to which the food stored in the bag would be contaminated by such micro-organisms can also be kept minimum. Thus, the food can be preserved for a longer period of time.
A conventional vacuum device comprises an operation housing defining a vacuum chamber wherein a plastic bag containing the product which is to be sealed is placed into the vacuum chamber. The air inside the plastic bag is then extracted and a heat sealer is installed for sealing the opening of the plastic bag. Due to the bulky size of the vacuum chamber, it is certainly not preferable for use in a confined domestic environment.
Over the years, in order to cater for the above problem, handheld vacuum device has been developed which comprises a vacuum housing communicating with a vacuum nozzle which is adapted to insert into the opening of the plastic bag for extracting air therein.
A common problem associated with such a handheld vacuum device is that it is very inconvenient during practical use. First of all, the handheld vacuum device needs some sorts of filtering to block unwanted particles or liquid droplets which have already retained in the plastic bag from entering to the vacuum pump. As a result, it is inconvenient to use in that it may require frequent replacement of filters.
Moreover, conventional handheld vacuum device usually comprises a vacuum sensor provided in the vacuum housing and electrically communicated with the vacuum pump for detecting the air pressure inside the plastic bag so as to automatically stop extracting air by the vacuum pump when all the air in the plastic bag has been extracted. The problem of this is that the performance of the sensor is often far from satisfactory so that the timing at which the vacuum pump stops operating does not match with the optimal air extraction inside the plastic bag. As a result, it may be that the vacuum pump is directed to stop extracting air when in fact the plastic bag is not become completely vacuum. Conversely, too insensitive the vacuum sensor leads to a result that the vacuum pump continues working when all the air inside the plastic bag has actually been extracted. Further vacuuming would lead to possible damage to the product contained in the plastic bag.
An example conventional art is that of U.S. Pat. No. 5,765,608 of Kristen, in which a vacuum device was disclosed as comprising a housing, a pump, a motor, and a vacuum sensor comprising a membrane. In that disclosure, a fluid flow tube is provided for fluid transfer and it allow the fluid to access to the vacuum sensor so as to optimally shut the motor off when a predetermined pressure inside the container is reached. A major problem for this conventional art is that the fluid flow tube plays a central role for fluid transfer within the vacuum device. This means that the positions of the relevant components, such as that of the motor, the pump, and the vacuum sensor, are dependent on the route and geometry of the fluid flow tube, which is elongated in shape. Specifically, the relevant components have to be distributed alone the fluid flow tube, making it very difficult to reduce the overall size of the housing.
Moreover, since the fluid flow tube is elongated in shape, from a practical perspective, it cannot be reasonably expected that along the fluid flow tube the fluid pressure is identical. As a result, the position of the vacuum sensor along the fluid flow tube becomes crucial in accurately assessing the fluid pressure at the container so as to determine an optimal time to stop vacuuming. However, it is very difficult, if not practically impossible, to find out an optimal position along the fluid flow tube for installing the vacuum sensor so as to achieve an optimal performance of the vacuum device.